A two-dimensional (2D) drawing package can be used to document the layout of a space. To compensate for lacking one real dimension, a single 2D drawing will only document a subset of the layout information and multiple drawings will be made of the same space. Further, different viewing orientations are often present in a drawing package. As a result, creating these drawing packages and understanding them requires a fair bit of skill. Unfortunately, these drawing packages also have a tendency to be ambiguous, miss some information, and be inconsistent between individual drawings. Generation of such a drawing package often consists of a team or individual with some sort of measuring and recording equipment (e.g. tape measure, laser measure, calipers for the former and notepad, computer for the latter).
Three-dimensional (3D) documentation improves upon the 2D drawing package in that it more naturally represents our 3D world. Classically, one way to generate 3D documentation would be to decipher a 2D drawing package and create a model of the space (computer aided design (CAD) or even a physical to-scale model). Through model-based definitions, a 3D CAD model can be used to generate 2D drawings. More recently, with 3D scanning technologies, it has become possible to scan the space and create documentation directly from the environment. There are a number of technologies which can be used to create 3D scans, such as Light Distance and Ranging (LiDAR), photogrammetry, real-world environment light, and sonar. Depending on the sensor and technique used, they result in point cloud data or triangulated mesh data. In both of these cases, they require additional processing to convert into a 3D CAD model or a 2D drawing package.
When a need to compare point clouds or meshes to 2D documentation arises, it is particularly challenging. Comparing 3D to 3D is natural. And comparing 3D CAD to 2D drawings is straightforward since 3D CAD can generate 2D drawings and the comparison can be made directly 2D to 2D. But with point clouds and meshes, the products aren't immediately comparable.